This invention relates to programmable electronic musical synthesizers and more particularly, to improved circuitry for automatically overriding a programmed parameter signal in favor of a manually operated synthesizer control function.
Electronic musical synthesizers are valued by musicians for their ability to create different qualities or timbres of sound. Whereas a piano or trumpet can create only a single characteristic timbre of sound and an organ can create at most a few dozen different timbres of sound, a typical synthesizer can create thousands of different timbres. In this specification and claims, timbre means the quality or characteristic of a sound. The quality or characteristic may be controlled by various sound parameters, such as, for example, loudness, octave, waveshape and harmonic spectrum.
Electronic musical synthesizers have been reduced in size and cost dramatically over the past decade. As a result, they are being used in live performances to a greater extent than ever before. This use of synthesizers has created a need for improved means for conveniently and accurately altering the vast number of different sound timbres which a synthesizer can create.
In order to generate a specific sound on a typical synthesizer, the performer must carefully set the position of many control knobs. There may be 40 to 100 such control knobs that require individual manipulation in order to achieve the the desired timbre of sound. During a live performance, the performer may want to change the timbre of the sound from one section of a composition to another. Typically, such a transition must be achieved in less than one second. Obviously, the transition cannot be made if a large number of control knobs must be repositioned.
In order to overcome the foregoing limitation of synthesizers, there have been attempts to fabricate programming circuits capable of storing the positions of the control knobs and automatically recalling the stored information in order to produce a desired timbre of sound. One such programming circuit is described by Thomas E. Oberheim in published Preprint No. 1172 (E3) entitled "A Programmer for Voltage-Controlled Synthesizers" which was presented to the Audio Engineering Society at its 55th convention, Oct. 29-Nov. 1, 1976. Although the Oberheim programming circuit provides a means of rapidly changing from one programmed timbre of sound to another, it does not provide means for conveniently altering stored information in response to manual operation of the synthesizer control knobs. That is, after recalling the stored information necessary to produce a selected timbre of sound, it would be desirable to provide suitable means for conveniently enabling the performer to manually operate one or more of the synthesizer control knobs to vary the associated sound parameters while otherwise operating the synthesizer in response to stored information.
U.S. Patent Application Ser. No. 921,786, filed July 3, 1978 in the names of David A. Luce and James L. Scott abandoned in favor of continuation application Ser. No. 152,431 filed May 22, 1980 and assigned to the assignee of the present invention, which application is incorporated herein by reference, discloses various "editing" circuits useful in association with a programmable synthesizer. According to this application, each sound parameter contributing to the programmed sound may be manually adjusted by operating a respective control knob, but only after an edit switch associated with the control knob has first been activated. The necessity for operating these edit switches, while not an overly burdensome limitation when used off-stage to edit a programmed timbre of sound, becomes quite objectionable when attempting to quickly override selected parameters of the programmed sound during a live, on-stage performance.